Technology - IPv6 5 - Multihoming & SHIM6

Synopsis

We discuss the SHIM6 protocol which is intended to provide IPv6 multihoming without relying on the BGP routing system. Multihoming is essential for providing reliable connection to the Internet, typically through two or more ISPs. We also discuss the BGP approach to multihoming, which may become the norm for IPv6 as it is for IPv4.

Table of Contents

• 1. Synopsis
• 2. Introduction
• 3. Types of Multihoming
  • 3.1 Multihoming a single host
  • 3.2 BGP and Autonomous System multihoming
    • 3.2.1 Regional Internet Registries (RIRs)
    • 3.2.2 Autonomous System (AS)
    • 3.2.3 BGP messages
    • 3.2.4 RIB and FIB
    • 3.2.5 BGP advertisements
    • 3.2.6 Multihoming example with two links
  • 3.3 The Default-Free-Zone (DFZ)
  • 3.4 Limitations of BGP multihoming
  • 3.5 Multihoming and Traffic Engineering
    • 3.5.1 Load balancing
    • 3.5.2 Cost and latency reduction
  • 3.6 Multihoming for small networks
• 4. PA or PI addresses for IPv6
  • 4.1 Provider Aggregatable (PA) IP addresses
    • 4.1.1 Difficulties with renumbering
  • 4.2 Provider Independent (PI) IP addresses
• 5. SHIM6
  • 5.1 IPv6 Multihoming goals
  • 5.2 IP addresses as identifiers and locators
    • 5.2.1 Rewriting source and destination addresses
    • 5.2.2 New headers
    • 5.2.3 SHIM6 messages
    • 5.2.4 Hash Based Addresses (HBA)
    • 5.2.5 Using the second ISP’s link
    • 5.2.6 No changes to global routing system
  • 5.3 Changing the conventional meaning of an IP address
  • 5.4 Interworking with Mobile IPv6
  • 5.5 Potential problems with SHIM6
  • 5.6 SHIM6 and the success of IPv6
  • 5.7 IPv6 may become a ‘routing swamp’
  • 5.8 MIPv6, SHIM6 and LISP
• 6. Related reports